The present invention relates to coupling a patient to a lithotripter and more particularly the invention relates to the coupling of shockwaves, generated by a a lithotripter, into the body of the patient who may rest on a particular bed or rest, or is otherwise suitably positioned for treatment.
In the past lithotripters were coupled to the body of a patient by means of water. In particular the lithotripter containing a source of shockwaves as well as facilities for focusing the shockwaves was placed in the vicinity of the body of the human beings and patient, and there was an open water bath or water cushion closed off by means of a flexible membrane for coupling the lithotripter to the body. Either the patient was submerged in a tank or a water cushion was interposed between the body of the patient and the lithotripter. There cannot be any question that such a closed water cushion is very practical in clinical practice. Disadvantages however are to be seen in the fact that this cushion, so to speak has to be operated. It has to be subjected to a very accurate pressure control and regulation. Moreover, unforseeable shifting of the patient may lead to folds in the cushion or may pose collision problems or the like.
U.S. Pat. No. 4,869,239 based on German patent 35 32 678, discloses a patient rest with a window and a water layer is provided in that window; various constructions are shown with and without covering flexible membrane. But even here any kind of pressure changes may result in undesired and unforseeable shift of the patient. It should be observed that shifting of the patient relative to the equipment has to be avoided at all costs. The equipment is positioned to establish a focus right in the concrement to be comminuted and unless the patient shifts such an out of focus situation is quite dangerous.